1. Field
The present disclosure relates generally to testing objects and, in particular, to vibration testing of objects.
2. Background
Vibrations are mechanical oscillations that may occur in different objects. Different objects react differently to vibrations. Additionally, objects also may react differently to vibrations of different intensities and different frequencies.
Vibration testing may be performed by introducing vibrations into a structure with a vibration generation device. The vibration generation device often takes the form of a shaker. The object under test may be attached to the shaker. The device under test may be connected to the shaker or placed on the shaker depending on the particular type of testing.
With relatively low frequency vibrations, a servo-hydraulic or electro-hydraulic shaker may be used. For higher frequencies, electro-dynamic shakers may be implemented.
The types of vibration tests may be a random test, a sine test, or some other type of test. With a random test, multiple intensities and frequencies may be tested. With a sine test, one frequency may be tested at a time. The object under test may be monitored during testing, after testing, or both, to identify the response of the object under test. In particular, the structural response of the object under test is often of interest.
With vehicles, a random test may be performed. A random test may use multiple intensities and frequencies at the same time. A random test may be performed to more closely replicate a real world environment. For example, with an automobile, the test may closely replicate the vibrations encountered on a road. When the object under test is a device for a spacecraft, the vibrations may simulate those encountered when the device is on a launch vehicle.
When objects are carried on launch vehicles, rockets, missiles, or other vehicles with rocket energies, vibration energies may be encountered as a result of combustion of energetic materials from a spacecraft propulsion system or as a result of various aerodynamic events. The high frequency vibration energy can be detrimental to objects that have sensitive electronics or optical components. These types of components may be present in objects such as guidance and navigational systems onboard a spacecraft. When these objects do not perform as desired, costly mission failures may occur.
As a result, when testing objects that may be placed on launch vehicles, rockets, missiles, or other similar vehicles, ultra-high vibration testing may be desired. Ultra-high vibration testing may use vibrations from about 10,000 Hz to about 100,000 Hz.
Conventional vibration testing systems, such as electro-dynamic shakers, have been used to simulate these events. These types of vibration testing systems have frequency limitations and cannot accurately duplicate the high frequency vibration environments. The limitations of currently used vibration testing systems can result in negative schedule impact and costly launch delays of satellites and other payloads.
Therefore, it would be advantageous to have a method and apparatus that takes into account at least some of the issues discussed above, as well as possibly other issues.